Electrotonic transform and EPSCs for WT and Q175+/- spiny projection neurons (Goodliffe et al 2018)

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Accession:236310
This model achieves electrotonic transform and computes mean inward and outward attenuation from 0 to 500 Hz input; and randomly activates synapses along dendrites to simulate AMPAR mediated EPSCs. For electrotonic analysis, in Elec folder, the entry file is MSNelec_transform.hoc. For EPSC simulation, in Syn folder, the entry file is randomepsc.hoc. Run read_EPSCsims_mdb_alone.m next with the simulated parameter values specified to compute the mean EPSC.
Reference:
1 . Goodliffe JW, Song H, Rubakovic A, Chang W, Medalla M, Weaver CM, Luebke JI (2018) Differential changes to D1 and D2 medium spiny neurons in the 12-month-old Q175+/- mouse model of Huntington's Disease. PLoS One 13:e0200626 [PubMed]
Citations  Citation Browser
Model Information (Click on a link to find other models with that property)
Model Type: Synapse;
Brain Region(s)/Organism: Striatum;
Cell Type(s): Neostriatum spiny neuron;
Channel(s):
Gap Junctions:
Receptor(s): AMPA;
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Detailed Neuronal Models; Membrane Properties; Electrotonus; Synaptic-input statistic;
Implementer(s):
Search NeuronDB for information about:  AMPA;
/
GoodliffeEtAl2018
Syn
tau_tables
bkkca.mod
cadyn.mod *
caL.mod
caL13.mod
caldyn.mod
can.mod
caq.mod *
car.mod
cat.mod
kaf.mod
kas.mod
kdr.mod
kir.mod *
krp.mod *
linearIclamp.mod
naf.mod
nap.mod
skkca.mod
stim.mod *
actionPotentialPlayer.hoc *
all_tau_vecs.hoc
analyticFunctions.hoc *
analyze_EPSC.m
aux_procs.hoc
baseline_values.txt
basic_procs.hoc
createFit_WTD1.m
electro_procs.hoc
fixnseg.hoc *
load_scripts.hoc
msp_template.hoc
PFC-V1_AddSynapses.hoc
PFC-V1_AddSynapses_fix.hoc
PFC-V1_AddSynapses_neg.hoc
PFC-V1_AddSynapses_negexp.hoc
plot_seClamp_i.ses
ran_test.hoc
randomepsc.hoc
ranstream.hoc
read_EPSCsims_mdb_alone.m
readcell.hoc
readNRNbin_Vclamp.m
                            
TITLE Submembrane calcium dynamics for N, P/Q, R calcium pool for NAcb cell

INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}

NEURON {
	SUFFIX cadyn
	USEION ca READ ica, cai WRITE cai
	RANGE pump, cainf, taur, drive
}

UNITS {
	(molar) = (1/liter)	
	(mM)	= (millimolar)
	(um)	= (micron)
	(mA)	= (milliamp)
	(msM)	= (ms mM)
}

CONSTANT {
	FARADAY = 96489		(coul)		: moles do not appear in units
}

PARAMETER {
    drive   = 10000  (1)
	depth	= 0.1	(um)		: depth of shell
	cainf	= 1e-5	(mM)		: gives eca = 108 mV
	taur	= 43	(ms)		: 
	kt	= 1e-4	(mM/ms)			: left over from Destexhe
	kd	= 1e-4	(mM)
	
	pump = 0.02					: turn pump up/down
}

STATE {
	cai		(mM) 
}

INITIAL {
	cai = cainf
}

ASSIGNED {
	ica		(mA/cm2)
	drive_channel	(mM/ms)
	drive_pump	(mM/ms)
}
	
BREAKPOINT {
	SOLVE state METHOD derivimplicit
}

DERIVATIVE state { 
	drive_channel =  - drive * ica / (2 * FARADAY * depth)
	    : this part converts the incoming calcium (from channels) into
	    : a corresponding change in internal concentration

	if (drive_channel <= 0.) { drive_channel = 0. }	: cannot pump inward

	drive_pump = -kt * cai / (cai + kd )		: Michaelis-Menten
	    : this accounts for calcium being pumped back out - M-M
	    : represents mechanism that is rate-limited by low ion conc.
	    : at one end and max pumping rate at high end
	
	cai' = ( drive_channel + pump*drive_pump + (cainf-cai)/taur )
	    : (cainf-cai)/taur represents exponential decay towards cainf
	    : at a time constant of taur from diffusive processe
}



COMMENT
Internal calcium concentration due to calcium currents and pump.

Differential equations.

 This file contains two mechanisms:
 1. Simple model of ATPase pump with 3 kinetic constants (Destexhe 1992)
       Cai + P <-> CaP -> Cao + P  (k1,k2,k3)

   A Michaelis-Menten approximation is assumed, which reduces the complexity
   of the system to 2 parameters: 
       kt = <tot enzyme concentration> * k3  -> TIME CONSTANT OF THE PUMP
	kd = k2/k1 (dissociation constant)    -> EQUILIBRIUM CALCIUM VALUE
   The values of these parameters are chosen assuming a high affinity of 
   the pump to calcium and a low transport capacity (cfr. Blaustein, 
   TINS, 11: 438, 1988, and references therein).  

   For further information about this this mechanism, see Destexhe, A. 
   Babloyantz, A. and Sejnowski, TJ.  Ionic mechanisms for intrinsic slow 
   oscillations in thalamic relay neurons. Biophys. J. 65: 1538-1552, 1993.


 2. Simple first-order decay or buffering:

       Cai + B <-> ...

   which can be written as:

       dCai/dt = (cainf - Cai) / taur

   where cainf is the equilibrium intracellular calcium value (usually
   in the range of 200-300 nM) and taur is the time constant of calcium 
   removal.

All variables are range variables

Written by Alain Destexhe, Salk Institute, Nov 12, 1992



Citations:
 
Destexhe, A. Babloyantz, A. and Sejnowski, TJ.  Ionic mechanisms for
intrinsic slow oscillations in thalamic relay neurons. Biophys. J. 65:
1538-1552, 1993.

Jackson MB, Redman SJ (2003) Calcium dynamics, buffering, and buffer
saturation in the boutons of dentate granule-cell axons in the hilus. J
Neurosci 23:1612-1621.

ENDCOMMENT